ORIGINAL PAPER Leaf water status, osmoregulation and secondary metabolism as a model for depicting drought tolerance in Argania spinosa Abdelghani Chakhchar 1 • Mouna Lamaoui 1 • Said Wahbi 2 • Abderrahim Ferradous 3 • Abdelhamid El Mousadik 4 • Saad Ibnsouda-Koraichi 5 • Abdelkarim Filali-Maltouf 6 • Cherkaoui El Modafar 1 Received: 3 October 2014 / Revised: 17 March 2015 / Accepted: 17 March 2015 Ó Franciszek Go ´rski Institute of Plant Physiology, Polish Academy of Sciences, Krako ´w 2015 Abstract The present investigation was undertaken to characterise and to distinguish four contrasting Argania spinosa ecotypes in terms of drought tolerance by explor- ing the changes of leaf water status, osmoregulation and secondary metabolism. A. spinosa plants corresponding to four contrasting ecotypes (Lks, Alz, Rab and Adm) were subjected to drought stress. The results exhibited that there was a significant decrease in predawn leaf water potential (W pd ), stomatal conductance (g s ) and leaf relative water content under the influence of the intensity and duration of drought stress. Negative and significant correlations were recorded between epicuticular wax load (EWL) and resi- dual transpiration rate. Electrolyte leakage (EL) increased significantly in leaves of plants under drought stress treatment compared to control plants. Furthermore, our data revealed that drought stress can induce shikimate and phenylpropanoid pathways in A. spinosa. A significant induction of phenylalanine ammonium lyase (PAL), shikimate dehydrogenase (SKDH) and cinnamate 4-hy- droxylase (C4H) enzymes and an increase in polyphenol content were recorded, of which Lks showed the highest induction and accumulation among ecotypes. Accumula- tion of polyphenols was positively correlated with the SKDH, PAL and C4H activities. The strong induction of secondary metabolism in Lks might be linked to its better ability of drought tolerance. The proline and soluble sugar content in leaves of all ecotypes increased substantially in parallel with the severity of stress-induced. According to canonical discriminant analysis of our data, the four eco- types were separated by the following physiological and biochemical parameters: EL, g s , EWL, soluble sugars and polyphenols. Keywords Argania spinosa Á Drought stress Á Shikimate and phenylpropanoid pathways Á Polyphenols Introduction The ways in which individual plants respond to abiotic stress are complex and varied (Rodziewicz et al. 2014). In Mediterranean ecosystem, the plants are subjected to a continuous and severe drought stress (Nogue ´s and Baker 2000). Some endemic species are well adapted to these conditions like argan tree in Morocco (Msanda et al. 2005; Dı ´az-Barradas et al. 2010). Responses to drought are spe- cies- and genotype-dependent characteristics. Unlike an- nual plants, trees inevitably suffer drought periods; thus, Communicated by P. Sowinski. & Abdelghani Chakhchar chakhchar.ckr@gmail.com 1 Laboratoire de Biotechnologie Valorisation et Protection des Agroressources, Faculte ´ des Sciences et Techniques Gue ´liz, Universite ´ Cadi Ayyad, 40 000 Marrakech, Morocco 2 Laboratoire de Biotechnologie et Physiologie Ve ´ge ´tale, Faculte ´ des Sciences Semlalia, Universite ´ Cadi Ayyad, 40 000 Marrakech, Morocco 3 Centre Re ´gional de la Recherche Forestie `re Marrakech, BP 12360 Ain Itti Ennakhil, Marrakech, Morocco 4 Laboratoire de Biotechnologie et Valorisation des Ressources Naturelles, Faculte ´ des Sciences, Universite ´ Ibn Zohr, Agadir, Morocco 5 Laboratoire de Biotechnologie Microbienne, Faculte ´ des Sciences et Techniques, Universite ´ Sidi Mohamed Ben Abdellah, Fe `s, Morocco 6 Laboratoire de Microbiologie et Biologie Mole ´culaire, Faculte ´ des Sciences, Universite ´ Mohammed V Agdal, Rabat, Morocco 123 Acta Physiol Plant (2015) 37:80 DOI 10.1007/s11738-015-1833-8